Yes, it ought to shorten its lifespan, but not as much as when its amperage throughput is highest, say making its host pull a hefty train. The decoder gets hotter as it manages amperage, and heat means skinning the lifespan.
When it is on hot track, it is sampling packets all the time in the signal looking for packets addressed to it. Even QSI's nifty coma-setting (double-press F9 three times in succession) won't spare the decoder from some incursion into its years because the decoder will respond when you next push F6 twice...meaning it is still paying attention to them packets.
Let's be reasonable, though. A radio plugged in, a clock radio, your TV, your anything with active circuitry, or that is on much of the time, has a finite life. We don't worry about it much, or we should probably not.